Method for preparing ethylene copolymer

Abstract

A process for preparing an ethylene copolymer in the presence of free-radical polymerization initiator at pressures from 150 MPa to 350 MPa and temperatures from 100° C. to 350° C., by copolymerizing ethylene and a comonomer having a C≡C bond and optionally further comonomers, wherein the comonomer having the C≡C bond is represented by formula wherein R 1 is hydrogen or methyl; X 1 is —CO—O— or —CO—NH—; R 2 is —CH 2 —O—, —O—CO—, —Si(CH 3 ) 2 —, —Si(CH 3 ) 2 —O— or —CR 5 R 6 — wherein R 5 and R 6 are independently selected from hydrogen, methyl, ethyl and hydroxyl; n is an integer from 1 to 32 and R 2 is same or different from each other when n is 2 to 32 ; and R 3 is —C≡C— and R 4 is hydrogen, C 1 -C 10 linear or branched alkyl, C 1 -C 10 linear or branched hydroxyalkyl or phenyl, or the unit R 3 -R 4 stands for wherein X 2 is F, Cl, Br or I.

The invention claimed is: 
     
       1. A process for preparing an ethylene copolymer in the presence of free-radical polymerization initiator at pressures in the range of from 150 MPa to 350 MPa and temperatures in the range of from 100° C. to 350° C. by copolymerizing ethylene and a comonomer having a C≡C bond and optionally further comonomers, wherein the comonomer having the C≡C bond is represented by formula 
       
         
           
           
               
               
           
         
       
       wherein
 R 1  is hydrogen or methyl; 
 X 1  is —CO—O— or —CO—NH—; 
 R 2  is —CH 2 —O—, —O—CO—, —Si(CH 3 ) 2 —, —Si(CH 3 ) 2 —O— or —CR 5 R 6 — wherein R 5  and R 6  are independently selected from hydrogen, methyl, ethyl and hydroxyl; 
 
       n is an integer from 1 to 32 and R 2  is same or different from each other when n is 2 to 32; and
 R 3  is —C≡C— and R 4  is hydrogen, C 1 -C 10  linear or branched alkyl, C 1 -C 10  linear or branched hydroxyalkyl or phenyl, or the unit R 3 -R 4  stands for 
 
       
         
           
           
               
               
           
         
       
       wherein X 2  is F, Cl, Br or I, and 
       wherein the copolymerization is performed in the presence of a chain transfer agent selected from the group consisting of propionaldehyde, n-heptane, propylene, propane, isopropanol and acetone. 
     
     
       2. The process according to  claim 1 , wherein the comonomer having the C≡C bond is compound (I) wherein X 1  is —CO—O—, R 2  is —CH 2 —, n is from 1 to 22, and R 3  is —C≡C—and R 4  is methyl or hydrogen or R 3 -R 4  stands for 
       
         
           
           
               
               
           
         
       
     
     
       3. The process according to  claim 1 , wherein the comonomer having the C≡C bond is selected from the group consisting of propargyl acrylate, propargyl methacrylate and 2- methyl-acrylic acid 3-(cyclooct-2-ynyloxy)-propyl ester. 
     
     
       4. The process according to  claim 1 , wherein the comonomer having the C≡C bond is propargyl methacrylate or propargyl acrylate. 
     
     
       5. The process according to  claim 4 , wherein the copolymerization is performed at temperatures of 150° C. to 210° C. and at pressures from 160 MPa and 250 MPa. 
     
     
       6. The process according to  claim 1 , wherein the amount of the comonomer having the C≡C bond is 0.1-10 mol % of the total weight of ethylene and all comonomers. 
     
     
       7. The ethylene copolymer obtained by the process of  claim 1 . 
     
     
       8. The ethylene copolymer according to  claim 7 , wherein the ethylene copolymer has a number average molecular weight M n  of at least 5.0 kg/mol and/or a weight average molecular weight M w  of at least 50 kg/mol. 
     
     
       9. An article comprising the ethylene copolymer according to  claim 7 . 
     
     
       10. The article according to  claim 9 , wherein the article is a film or sheet. 
     
     
       11. The article according to  claim 10 , wherein the film is or is a component of food packaging , consumer durable packaging, disposable diapers, textiles, agricultural film, shrink film, medical packaging, cable insulations, mulching film, protective film, or polymer coatings. 
     
     
       12. The article according to  claim 11 , wherein the film or sheet has a thickness of 5 to 500 micrometers. 
     
     
       13. The article according to  claim 9 , wherein the article is an injection moulded article, a blow moulded article, a sheet vacuum formed article, or a polymer coating. 
     
     
       14. The article according to  claim 13 , wherein the article is a container, bottle, rigid packaging, pail, or tray. 
     
     
       15. A process for preparing an ethylene copolymer in the presence of free-radical polymerization initiator at pressures in the range of from 150 MPa to 350 MPa and temperatures in the range of from 100° C. to 350° C. by copolymerizing ethylene and a comonomer having a C≡C bond and optionally further comonomers, wherein the comonomer having the C≡C bond is represented by formula 
       
         
           
           
               
               
           
         
       
       wherein
 R 1  is hydrogen or methyl; 
 X 1  is —CO—O— or —CO—NH—; 
 R 2  is —CH 2 —O—, —O—CO—, —Si(CH 3 ) 2 —, —Si(CH 3 ) 2 —O— or —CR 5 R 6 — wherein R 5  and R 6  are independently selected from hydrogen, methyl, ethyl and hydroxyl; 
 n is an integer from 1 to 32 and R 2  is same or different from each other when n is 2 to 32; and 
 R 3  is —C≡C— and R 4  is hydrogen, C 1 -C 10  linear or branched alkyl, C 1 -C 10  linear or branched hydroxyalkyl or phenyl, or the unit R 3 -R 4  stands for 
 
       
         
           
           
               
               
           
         
       
       wherein X 2  is F, Cl, Br or I, and 
       wherein the process is performed in a tubular reactor. 
     
     
       16. A process for preparing an ethylene copolymer in the presence of free-radical polymerization initiator at pressures in the range of from 150 MPa to 350 MPa and temperatures in the range of from 100° C. to 350° C. by copolymerizing ethylene and a comonomer having a C≡C bond and optionally further comonomers, wherein the comonomer having the C≡C bond is represented by formula 
       
         
           
           
               
               
           
         
       
       wherein
 R 1  is hydrogen or methyl; 
 X 1  is —CO—O—; 
 R 2  is —CH 2 —; 
 n is an integer from 1 to 22; and 
 R 3  is —C≡C— and R 4  is methyl or hydrogen or R 3 -R 4  stands for 
 
       
         
           
           
               
               
           
         
       
     
     
       17. The process according to  claim 16 , wherein the copolymerization is performed in the presence of a chain transfer agent selected from the group consisting of propionaldehyde, n-heptane, propylene, propane, isopropanol and acetone.